Whistle pen



FIG. 1 is a perspective view of a whistle pen, showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof;

FIG. 8 is another perspective view thereof; and,

FIG. 9 is a partly expanded perspective view thereof.

The broken lines shown on FIGS. 7 and 9 are for environmental purposes only and form no part of the claimed design. 

The ornamental design for a whistle pen, as shown and described. 